Extremely low refrigerant charge beverage display cooler technology using propane

One way to mitigate the flammability risk of propane used in light commercial applications such as beverage coolers is rigorous reduction of refrigerant charge to levels that are substantially below legal limits. This task has been accomplished by employing experimentally validated simulation models that can be used to reliably predict the refrigerant charge in each component at different ambient conditions, focusing on the compressor oil type and charge amount which dissolves large quantities of propane. The other component with significant potential to reduce refrigerant charge is the condenser; low internal volumes are desired that can provide a balance between refrigerant charge, heat transfer, and pressure drop. A serpentine style microchannel condenser design featuring low fin density was implemented. The improvements along with further optimizations were implemented into a beverage cooler holding 700 cans with a volume of 355 ml per can. The achieved cooling capacity was on the order of 1 kW featuring a propane refrigerant charge of less than or equal to 50 g. The performance of the redesigned beverage display cooler was experimentally validated at an ambient temperature of 32.2°C and it was found that all of the manufacturers' pull-down and energy consumption test requirements were successfully achieved.